Probing the dynamics of dissociation of methane following core ionization using three-dimensional molecular-frame photoelectron angular distributions

Williams, Joshua; Trevisan, C. S.; Schöffler, M. S.; Jahnke, T.; Bocharova, I.; Kim, H; Ulrich, B.; Wallauer, R.; Sturm, Felix; Rescigno, T. N.; Belkacem, A.; Dörner, R.; Weber, Thorsten; McCurdy, C. William; Landers, A. L.

doi:10.1088/0953-4075/45/19/194003

Cited by 29 publications

(47 citation statements)

References 27 publications

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“…17,18 In particular, it has been shown that, in some cases, MFPADs associated with very slow electrons provide a direct imaging of molecular structure. 19,20 A common denominator in the above examples is that photoelectron spectra must be recorded (at least) as a function of the electron ejection angle. This requires the use of rather sophisticated coincidence setups with high angular resolution and high detection efficiency, 21,22 which are not always available or applicable.…”

Section: Introductionmentioning

confidence: 99%

Intramolecular photoelectron diffraction in the gas phase

Ueda

Miron

Plésiat

et al. 2013

The Journal of Chemical Physics

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We report unambiguous experimental and theoretical evidence of intramolecular photoelectron diffraction in the collective vibrational excitation that accompanies high-energy photoionization of gas-phase CF 4 , BF 3 , and CH 4 from the 1s orbital of the central atom. We show that the ratios between vibrationally resolved photoionization cross sections (v-ratios) exhibit pronounced oscillations as a function of photon energy, which is the fingerprint of electron diffraction by the surrounding atomic centers. This interpretation is supported by the excellent agreement between first-principles static-exchange and time-dependent density functional theory calculations and high resolution measurements, as well as by qualitative agreement at high energies with a model in which atomic displacements are treated to first order of perturbation theory. The latter model allows us to rationalize the results for all the v-ratios in terms of a generalized v-ratio, which contains information on the structure of the above three molecules and the corresponding molecular cations. A fit of the measured v-ratios to a simple formula based on this model suggests that the method could be used to obtain structural information of both neutral and ionic molecular species.

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Section: Introductionmentioning

confidence: 99%

Intramolecular photoelectron diffraction in the gas phase

Ueda

Miron

Plésiat

et al. 2013

The Journal of Chemical Physics

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“…Very recently, MFPADs for the CH 4 molecule have been determined by detecting the photoelectron in coincidence with the positively charged fragments that result from dissociation following prompt Auger decay of CH + 4 [14,15]. The surprising result is that, at very low photoelectron energies, the electron is mainly ejected along the bond directions.…”

Section: Introductionmentioning

confidence: 99%

Relationship between polarization-averaged molecular-frame photoelectron angular distributions and geometry

2013

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We present a theoretical study of vibrationally resolved and unresolved molecular-frame photoelectron angular distributions (MFPADs) resulting from K-shell photoionization of N 2 , CO, C 2 H 2 , NH 3 , CH 4 , CF 4 , BF 3 , and SF 6 in the range of photoelectron energies 0-500 eV. We show that the MFPADs of NH 3 and CH 4 , averaged over the polarization direction, image the molecular geometry at very low energies but also at selected higher energies. For all other molecules, the MFPADs do not image the system's geometry. However, for molecules containing heavy atoms in the periphery, CF 4 , BF 3 , and SF 6 , and for N 2 and CO, the polarization-averaged MFPADs reflect the partial accumulation of the photoelectron density in the region surrounded by the peripheral atoms. For energies at which this accumulation occurs, the MFPADs encode information about the three dimensional arrangement of the system. In general, the polarization averaged MFPADs remain quite anisotropic even at photoelectron energies as high as 500 eV.

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“…Indications of molecular frame anisotropy at low energies are given also by are given also by the occurrence of "knockout" secondary ionization processes induced by the primary photoelectron [27]. On the other hand, it was also observed that MFPAD rapidly approaches isotropic distribution with increasing electron energy [26] and we thus believe that in the range of strong recoil effects the approximation of isotropic orientationally averaged MFPAD is well justified, although the recoil model would benefit from more detailed information on MFPADs at the energies of interest.…”

Section: Analysis a Static-exchange Dft Resultsmentioning

confidence: 96%

“…On one hand, recent results using the COLTRIMS (cold target recoil ion momentum spectroscopy) technique have shown that at low photoelectron kinetic energies the MFPADs, even after averaging over the direction of the polarization vector, can be strongly anisotropic (e.g., photoemission preferentially along the molecular bonds in methane) [26]. Indications of molecular frame anisotropy at low energies are given also by are given also by the occurrence of "knockout" secondary ionization processes induced by the primary photoelectron [27].…”

Section: Analysis a Static-exchange Dft Resultsmentioning

confidence: 99%

Effects of molecular potential and geometry on atomic core-level photoemission over an extended energy range: The case study of the CO molecule

et al. 2013

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We report an experimental and theoretical study of single-molecule inner-shell photoemission measured over an extended range of photon energies. The vibrational intensity ratios I (ν = 1)/I (ν = 0) from the C 1s photoelectron spectra of carbon monoxide, although mostly determined by the bond length change upon ionization, are shown to be affected also by photoelectron recoil and by scattering from the neighboring oxygen atom. Static-exchange density functional theory (DFT) is used to encompass all these effects in a unified theoretical treatment. The ab initio calculations show that the vibrational ratio as a function of the photoelectron momentum is sensitive to both the ground-state internuclear distance and its contraction upon photoionization. We present a proof-of-principle application of DFT calculations as a quantitative structural analysis tool for extracting the dynamic and static molecular geometry parameters simultaneously.

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Probing the dynamics of dissociation of methane following core ionization using three-dimensional molecular-frame photoelectron angular distributions

Cited by 29 publications

References 27 publications

Intramolecular photoelectron diffraction in the gas phase

Intramolecular photoelectron diffraction in the gas phase

Relationship between polarization-averaged molecular-frame photoelectron angular distributions and geometry

Effects of molecular potential and geometry on atomic core-level photoemission over an extended energy range: The case study of the CO molecule

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